Nowcasting (Short-Term Forecasting) of Influenza Epidemics in Local Settings, Sweden, 2008-2019

Emerg Infect Dis. 2020 Nov;26(11):2669-2677. doi: 10.3201/eid2611.200448.


The timing of influenza case incidence during epidemics can differ between regions within nations and states. We conducted a prospective 10-year evaluation (January 2008-February 2019) of a local influenza nowcasting (short-term forecasting) method in 3 urban counties in Sweden with independent public health administrations by using routine health information system data. Detection-of-epidemic-start (detection), peak timing, and peak intensity were nowcasted. Detection displayed satisfactory performance in 2 of the 3 counties for all nonpandemic influenza seasons and in 6 of 9 seasons for the third county. Peak-timing prediction showed satisfactory performance from the influenza season 2011-12 onward. Peak-intensity prediction also was satisfactory for influenza seasons in 2 of the counties but poor in 1 county. Local influenza nowcasting was satisfactory for seasonal influenza in 2 of 3 counties. The less satisfactory performance in 1 of the study counties might be attributable to population mixing with a neighboring metropolitan area.

Keywords: Sweden; epidemiology; evaluation research; human influenza; infectious disease; influenza; modelling; respiratory diseases; respiratory infections; signal detection analysis; surveillance; vaccine-preventable diseases; viruses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Epidemics*
  • Forecasting
  • Humans
  • Influenza, Human* / epidemiology
  • Prospective Studies
  • Seasons
  • Sweden / epidemiology